The invention pertains to a handling device, in particular for handling boards and foils, with a number of suction grippers located in a plane.
For example, in the manufacture of circuitboards, the circuitboards have to be positioned, turned and moved along to the next processing station during the various manufacturing processes. Positioning and movement of the circuitboards is effected in a known manner with a handling device in which a number of suction grippers are positioned in a plane. The suction grippers are lowered by means of a positioning device onto the particular circuitboard, and a suction pressure which is less than atmospheric pressure is then applied in order to secure the plate pneumatically to the handling device. The circuitboard can then be moved to the next desired working position by means of the positioning device.
However, this known handling device is suitable only for relatively stiff circuitboards with a board thickness of more than 0.5 mm, for example. Thinner circuitboards would necessarily be irreversibly deformed by the suction gripper itself, even at low suction pressure, so that thin circuitboards or conductor foils of this kind cannot be moved with this type of handling device.
For positioning and handling these thin boards or foils, air-permeable suction plates are known that generate a uniformly small suction pressure across their entire vacuum surface, so that thin boards or foils can be pneumatically placed on this suction surface and will not be deformed. However, these suction plates are not suitable for handling stiffer, more rigid boards, since these are not usually perfectly smooth due to their manufacture, and thus will not make a full-surface contact. Thus, these boards will not stick sufficiently to the suction plate.
Therefore, in practice, depending on the particular thickness of the board, the particular board under manufacture will be exposed to different handling devices, which may have to be replaced when switching the manufacture from thinner to thicker boards. This is very cumbersome and labor-intensive, in particular for rapid alternation in manufacture.
One problem of the present invention consists in the creation of a handling device which is equally suitable for handling thicker boards as well as thinner boards and foils.
This problem is solved according to this invention, in that a suction plate is provided which is made of a porous material or sintered material and to which a suction pressure can be applied, said suction plate being equipped with openings permitting the passage of the suction grippers, and in that positioning means are provided by means of which in a first position setting the suction grippers extend beyond the suction surface of the suction plate and by means of which in a second position setting, the suction grippers are moved back into the openings such that they no longer extend beyond the suction surface of the suction plate.
This handling device can be switched between the two position settings by a simple actuation of the positioning means, such that the first position setting will be used for handling thicker and stiffer boards, and the second position setting is used for handling very thin boards and foils, but without damaging them. Refitting the work stations is thus no longer necessary, and production can be switched very quickly and easily from thin boards and foils to thick boards and vice-versa. This changeover can occur under program control so that refitting downtimes are eliminated.
Favorable refinements and improvements to the handling device specified in claim 1 are possible due to the features presented in the dependent claims.
Preferably, control means are provided for supplying suction to the suction plate on the one hand, and to the suction grippers on the other hand, wherein the suction grippers are supplied with suction pressure only in the first position setting. In this manner, the suction grippers will be prevented from picking up the thin foil or board and pulling them into the openings and possibly damaging them, despite the fact that they are a certain distance away from them in the second position setting. Thus, in a first position setting, the suction pressure for the suction plate can be preferably switched off in order to prevent unnecessary usage. In addition, suction pressure can be saved in that, for smaller manipulated boards, only those suction grippers or only those regions of the suction plate which correspond essentially to the structure of the board will be supplied with suction pressure.
In yet another favorable design configuration of the invention, the suction plate is tightly connected with a suction pressure supply plate on the side facing away from the suction surface; said supply plate is provided with at least one suction pressure supply connector and this at least one suction pressure supply connector is connected to at least one planar cavity between the plates, and said cavity is formed by a recess in at least one of the plates. Due to the planar cavity or cavities, the largest possible surface area of the suction plate will be exposed to the suction pressure, which in turn means that the suction pressure application to the vacuum surface will be as uniform as possible. The suction pressure supply plate is also equipped with openings for the suction grippers which correspond to those in the suction pressure plate.
In this regard, it is preferable to design the positioning means at least as a pneumatic, variable-position actuator that is located between the suction plate and a retaining device for the suction grippers, where said retaining device has, in particular, one retaining plate. Thus, at least one actuator [of the positioning means] will be advantageously designed as a contraction element, which has a contraction tube extending between two head pieces and which experiences a length contraction when exposed to internal pressure. The structural and functional principle of contraction elements of this kind can correspond, for example, to that described in the brochure xe2x80x9cFluidic Muscle,xe2x80x9d or in EP 016 1750 B1, presented by the applicant. Due to this type of design of the (at least) one actuator, the positioning of the vacuum plate or of the suction gripper can be controlled very accurately, so that low costs and a simple, low-wear design will be additional advantages. With conventional actuators, height positioning over a range of 10 mm is possible, for example, in increments of one-tenth, but only with very great expense for the mechanism and control equipment, since there is a danger of kinking, in particular for large-surface vacuum plates of 600xc3x97800 mm, for instance.
In this regard, it is preferable to provide a stop device that limits movements of the plates toward each other in the direction of the first position setting, so that the projection of the suction gripper past the vacuum surface can be adjusted very precisely. For precision movement of the retaining device, a control device can be provided to guide the motion of the retaining device relative to the suction plate.
Particularly precise positioning of the contraction element or elements can be achieved by providing a proportional pressure control valve which is connected to the positioning means and which adjusts the internal pressure according to a specified setpoint. By means of an electrical, setpoint specification module, any particular analog setpoints can be adjusted, for example, by means of an integrated potentiometer. A digital determination of setpoints is also possible, of course.
Advantageously, a positioning device can be provided which positions the entire apparatus composed of the at least one or more suction plates, the retaining device for the suction grippers, and the at least one or more actuators, and which is designed to implement positioning movements at least in two directions in space, one of these corresponding to the direction of movement of the actuator. In addition to the forward movement of the board being handled, for example, from one workstation to the next, the vacuum plate can thus be moved very accurately in the vertical direction up to the thin board or foil to be grasped, merely by first performing a rough positioning by the positioning device and then effecting a precise approach of the vacuum plate by means of the contraction element or elements.